80



     the current value of location 19, therefore is given a new color
     value every 4.27 seconds.

Bytes 80 to 122 ($50 to $7A) are used by the screen editor and display
handler.

80             50             TEMP
     Temporary register used by the display handler in moving data to
     and from screen. Also called TMPCHR.

81             51             HOLD1
     Same as location 80. It is used also to hold the number of Display
     List entries.

82             52             LMARGN
     Column of the left margin of text (GR.0 or text window only).
     Zero is the value for the left edge of the screen; LMARGN is
     initialized to two. You can POKE the margin locations to set them
     to your specific program needs, such as POKE 82,10 to make the
     left margin start ten locations from the edge of the screen.

83             53             RMARGN
     Right margin of the text screen initialized to 39 ($27). Both
     locations 82 and 83 are user-alterable, but ignored in all
     GRAPHICS modes except zero and the text window.
     Margins work with the text window and blackboard mode and are
     reset to their default values by pressing RESET. Margins have no
     effect on scrolling or the printer. However, DELETE LINE and
     INSERT LINE keys delete or insert 40 character lines (or delete
     one program line), which always start at the left margin and wrap
     around the screen edge back to the left margin again. The right
     margin is ignored in the process. Also, logical lines are always
     three physical lines no matter how long or short you make those
     lines.
     The beep you hear when you are coming to the end of the logical
     line works by screen position independent of the margins. Try
     setting your left margin at 25 (POKE 82,25) and typing a few lines
     of characters. Although you have just a few characters beyond
     60, the buzzer will still sound on the third line of text.

84             54             ROWCRS
     Current graphics or text screen cursor row, value ranging from
     zero to 191 ($BF) depending on the current GRAPHICS mode
     (maximum number of rows, minus one). This location, together	
     with location 85 below, defines the cursor location for the next
     element to be read/written to the screen. Rows run horizontally,
     left to right across the TV screen. Row zero is the topmost line;
     row 192 is the maximum value for the bottom-most line.